Killed Dominus and I reached Act 4. The first part of the fight wasn't too hard, just having too deal with two groups of three mini bosses and the enemies the kept spawning.
Though after I killed him his second form caught me by surprise and the raining blood attack was bonkers until I understood how it worked. The attack will reach all the place and the only point safe is near Dominus, but what was my worst enemy was my old laptop, the rain effect made the FPS drop to single digits reaching, so it ended making avoid some attacks pretty difficult but in the end I killed him with 4 or 5 deaths under my belt, nothing bad.